williatw wrote:Let us see now…what is the ultimate known example of greenhouse gas warming via CO2? The planet Venus.Venus is 67 million miles from the Sun; the Earth is 93 million. By the inverse square law: 932 /672 = 1.93. So Venus gets roughly twice the solar constant Earth gets. So I would expect it to be twice as hot. Venus surface temp averages about 900F; converted to Kelvin ((900-32)*5/9) = 482C+273.15 = 755K. Earth’s ave. temp is 287K. So Venus is 755/287 = 2.63 X hotter than earth. Or about 36% hotter than what you would expect from its closer distance to the Sun. But wait as we all know Venus has an atmosphere that is almost all CO2; and at 90atm pressure. Venus gravity at it surface is approx. 0.8 that of Earth’s; so 90/.8 = 112.5. So the mass of Venus’s atmosphere all CO2, a greenhouse gas, is approx. over a hundred times that of Earth’s; but only apparently adds about 36% higher temp over Earth’s than what you would expect just from its closer proximity to the Sun. Conclusion CO2 must be a relatively weak greenhouse gas. It would suggest we probably don't need to lose too much sleep worrying about the effect of the approx. 350ppm CO2 in our two orders of magnitude less massive total atmosphere. Also explains perhaps why my favorite Martian potential terraforming gas NF3 (Nitrogen Trifluoride) can be 17,000 times more powerful than CO2; it is because CO2 is obviously a wimpy greenhouse gas. Comments anyone?

That's not the whole story, if CO2 was the only thing involved then Venus wouldn't be nearly as hot as it is today. Sulfur dioxide is what's really causing the insanely high temps. In relatively small quantities that stuff isn't much threat but get enough of it together and it creates a blanket that doesn't allow anything out. If whatever caused all that SO2 hadn't of happened then Venus might of actually developed life.

williatw wrote:Let us see now…what is the ultimate known example of greenhouse gas warming via CO2? The planet Venus.Venus is 67 million miles from the Sun; the Earth is 93 million. By the inverse square law: 932 /672 = 1.93. So Venus gets roughly twice the solar constant Earth gets. So I would expect it to be twice as hot. Venus surface temp averages about 900F; converted to Kelvin ((900-32)*5/9) = 482C+273.15 = 755K. Earth’s ave. temp is 287K. So Venus is 755/287 = 2.63 X hotter than earth. Or about 36% hotter than what you would expect from its closer distance to the Sun. But wait as we all know Venus has an atmosphere that is almost all CO2; and at 90atm pressure. Venus gravity at it surface is approx. 0.8 that of Earth’s; so 90/.8 = 112.5. So the mass of Venus’s atmosphere all CO2, a greenhouse gas, is approx. over a hundred times that of Earth’s; but only apparently adds about 36% higher temp over Earth’s than what you would expect just from its closer proximity to the Sun. Conclusion CO2 must be a relatively weak greenhouse gas. It would suggest we probably don't need to lose too much sleep worrying about the effect of the approx. 350ppm CO2 in our two orders of magnitude less massive total atmosphere. Also explains perhaps why my favorite Martian potential terraforming gas NF3 (Nitrogen Trifluoride) can be 17,000 times more powerful than CO2; it is because CO2 is obviously a wimpy greenhouse gas. Comments anyone?

That's not the whole story, if CO2 was the only thing involved then Venus wouldn't be nearly as hot as it is today. Sulfur dioxide is what's really causing the insanely high temps. In relatively small quantities that stuff isn't much threat but get enough of it together and it creates a blanket that doesn't allow anything out. If whatever caused all that SO2 hadn't of happened then Venus might of actually developed life.

So, just to be clear, you are supporting williatw's main premise, right? I think the Venusian environment is far too complex to casually come up with these kind of conclusions (as is Earth's) but I find this line of reasoning rather interesting.

Anyone have a link to a modern, non-politicized, scientific analysis of all the contributing factors in the Venusian heat?

Working out the details of the GHE is really complex, and few people seem to understand the basics.

For example, the earth's atmosphere is opaque to IR wavelengths. This causes people with knee-jerk reactions to think that CO2 is saturated and increasing it can have no effect.

The issue however is the height in the atmosphere over which radiative transport occurs. That matters because the higher up you go the colder it gets. Altering CO2 concentration changes this "transparent to IR" height.

The theory is well understood, but quite complex, even without clouds. With clouds things are a bit random but luckily we now have good experimental data directly validating the greenhouse effect and quantifying it:

williatw wrote:Let us see now…what is the ultimate known example of greenhouse gas warming via CO2? The planet Venus.Venus is 67 million miles from the Sun; the Earth is 93 million. By the inverse square law: 932 /672 = 1.93. So Venus gets roughly twice the solar constant Earth gets. So I would expect it to be twice as hot. Venus surface temp averages about 900F; converted to Kelvin ((900-32)*5/9) = 482C+273.15 = 755K. Earth’s ave. temp is 287K. So Venus is 755/287 = 2.63 X hotter than earth. Or about 36% hotter than what you would expect from its closer distance to the Sun. But wait as we all know Venus has an atmosphere that is almost all CO2; and at 90atm pressure. Venus gravity at it surface is approx. 0.8 that of Earth’s; so 90/.8 = 112.5. So the mass of Venus’s atmosphere all CO2, a greenhouse gas, is approx. over a hundred times that of Earth’s; but only apparently adds about 36% higher temp over Earth’s than what you would expect just from its closer proximity to the Sun. Conclusion CO2 must be a relatively weak greenhouse gas. It would suggest we probably don't need to lose too much sleep worrying about the effect of the approx. 350ppm CO2 in our two orders of magnitude less massive total atmosphere. Also explains perhaps why my favorite Martian potential terraforming gas NF3 (Nitrogen Trifluoride) can be 17,000 times more powerful than CO2; it is because CO2 is obviously a wimpy greenhouse gas. Comments anyone?

That's not the whole story, if CO2 was the only thing involved then Venus wouldn't be nearly as hot as it is today. Sulfur dioxide is what's really causing the insanely high temps. In relatively small quantities that stuff isn't much threat but get enough of it together and it creates a blanket that doesn't allow anything out. If whatever caused all that SO2 hadn't of happened then Venus might of actually developed life.

So, just to be clear, you are supporting williatw's main premise, right? I think the Venusian environment is far too complex to casually come up with these kind of conclusions (as is Earth's) but I find this line of reasoning rather interesting.

Anyone have a link to a modern, non-politicized, scientific analysis of all the contributing factors in the Venusian heat?

Yes williatw is correct in that CO2 is a fairly weak greenhouse gas. I was saying that it's actually weaker then he formulated because the SO2 in the atmosphere is what drives the runaway greenhouse effect, CO2 by itself couldn't accomplish that because it's transparent to too many wavelengths of radiation. SO2 vapor on the other hand is opaque to many of those wavelengths and would act as a mirror reflecting, reflecting both up and down. For Venus, earlier in it's existence, before it had the massive SO2 cloud cover, it would of acted like the earth in that it would of been balanced in radiated in / out. Some event happened, most likely immense volcanic activity, that expelled a ridiculous amount of Sulfur into the atmosphere that mixed and started forming clouds. Clouds reflected light outward but also acted to keep warmth inward in a similar way to our own H2O clouds. But because there is no way for the Sulfur to be reabsorbed or regulated it ended up keeping more in then it let out and eventually resulted in Venus's oceans boiling off and creating those insane atmosphere conditions. At least that's the current theory as CO2 itself doesn't come close to holding in that much heat and it can't explain the SO2 clouds. Mars on the other hand has a similar atmosphere content, though it's far thinner with no Sulfur or other cloud forming agents. Without clouds there is no way you can get any significant greenhouse effects.

For the earth, H2O vapor is our big greenhouse gas, CO2 itself isn't worth much and never was. It's too limited in it's range of absorbed light, so limited that after 180~220 ppm it becomes essentially worthless. But don't let a liberal hear you say that.

palladin9479 wrote:Yes williatw is correct in that CO2 is a fairly weak greenhouse gas. I was saying that it's actually weaker then he formulated because the SO2 in the atmosphere is what drives the runaway greenhouse effect, CO2 by itself couldn't accomplish that because it's transparent to too many wavelengths of radiation. SO2 vapor on the other hand is opaque to many of those wavelengths and would act as a mirror reflecting, reflecting both up and down. For Venus, earlier in it's existence, before it had the massive SO2 cloud cover, it would of acted like the earth in that it would of been balanced in radiated in / out.

For the earth, H2O vapor is our big greenhouse gas, CO2 itself isn't worth much and never was. It's too limited in it's range of absorbed light, so limited that after 180~220 ppm it becomes essentially worthless. But don't let a liberal hear you say that.

This is from Wikipedia about the hypothesized "Snowball Earth"

Breaking out of global glaciation

The carbon dioxide levels necessary to unfreeze the Earth have been estimated as being 350 times what they are today, about 13% of the atmosphere.[54] Since the Earth was almost completely covered with ice, carbon dioxide could not be withdrawn from the atmosphere by release of alkaline metal ions weathering out of siliceous rocks. Over 4 to 30 million years, enough CO2 and methane, mainly emitted by volcanoes, would accumulate to finally cause enough greenhouse effect to make surface ice melt in the tropics until a band of permanently ice-free land and water developed;[55] this would be darker than the ice, and thus absorb more energy from the Sun — initiating a "positive feedback".

In other words just to end the permanent Ice Age that was "Snowball Earth" it took an estimated CO2 levels 350 X times current levels 13% of the atmosphere; an amount that would be fatal to humans as an aside. That high just to start to nudge the earth back to a "normal" temperature range. This would strongly imply that CO2 is a decidedly wussy green house gas. And further more since it is their (the scientists') estimate, it must be known to be such by the scientific community.

On an interesting note about Venus's atmosphere is how layered it is. The bottom most layer is composed almost entirely of CO2 and is something like 99% of it's total atmosphere. The pressure is so high that CO2 is no longer a gas, it's become a super critical fluid and behaves accordingly. It's like a giant hot 30km deep Ocean that covers the entire planet. Above that is where you find the SO2 clouds which act to reflect away most visible sunlight while also reflecting down any light that does make it through and bounces off the surface.

Venus's atmosphere is so radically different from Earths that trying to use it as a model for CO2 greenhouse effect is pure stupidity. Earth has a cool H2O ocean that's only 3.7km deep while Venus is a 30km deep "Ocean" comprised of CO2 at super critical temperatures.

In other words just to end the permanent Ice Age that was "Snowball Earth" it took and estimated CO2 levels 350 X times current levels 13% of the atmosphere; an amount that would be fatal to humans as an aside. That high just to start to nudge the earth back to a "normal" temperature range. This would strongly imply that CO2 is a decidedly wussy green house gas.

That's because it only absorbs and remits radiation from a very small range, otherwise it's transparent. Greenhouse effects are primarily driven by cloud formations, the more you have the stronger the effect. CO2 itself doesn't form clouds and thus there needs to be another element present in order for a strong greenhouse effect to exist. On earth its our H2O cloud formations, if for some reason we end up short on H2O in the sky, you can expect temperatures to plummet very fast. On the other hand if there is a lot of H2O cloud formations, especially lower altitude ones, then you can expect it to get warm very fast. Cloud formations at high altitudes also serve to reflect light away so there is a built in regulatory system that tends to stabilize the atmosphere, as long as there isn't some cataclysmic event that destabilizes everything. Sudden surges of volcanic activity, large meteor impacts, things on that scale, not a bunch of smart monkeys running around burning shit for a hundred years. Planetary activities tend to be measured on cosmic scales which count time in the millions of years.

Humans think entirely too much of themselves if they think they can actually destabilize an entire planets atmosphere regulatory system in, what is to the planet, less then a blink of an eye. We are insignificant when compared to such cosmic scales.

palladin9479 wrote:... Sudden surges of volcanic activity, large meteor impacts, things on that scale, not a bunch of smart monkeys running around burning shit for a hundred years. Planetary activities tend to be measured on cosmic scales which count time in the millions of years.

Sudden surges of volcanic activity, large meteor impacts, things on that scale, not a bunch of smart monkeys running around burning shit for a hundred years. Planetary activities tend to be measured on cosmic scales which count time in the millions of years.

Humans think entirely too much of themselves if they think they can actually destabilize an entire planets atmosphere regulatory system in, what is to the planet, less then a blink of an eye. We are insignificant when compared to such cosmic scales.

Large meteors, mega-volcanoes - destablise instantly.

Glaciation feedback changes take tens of thousands of years.

Ecosystem changes (extinction of significant amounts of species due to environment change) can be anything from 10 - 1000 years or more for example when plants learnt to photosynthesise.

smart monkeys burning shit:

No problem if it was shit. Per capita per year mass limited to 200g*356 days = 70kg

But we have per capita per year usage of >10 tons CO2 equiv fossil fuels in developed countries.

That is 100X the smart monkey shit norm, and becomes significant when there are enough smart monkeys. Humans currently live, supported by technology, at a density impossible ever before in evolutionary history. That is a shed-load of shit. And 100X more CO2 form fossil fuels.

You make one incredibly important point. currently we are in a state that our population density is out of proportion with our available energy. If history has shown us anything its that when you reach this level in development; your civilization must find a denser source of energy or fall back to a more sustainable level. Maybe this is the real answer to the Fermi paradox.

Sudden surges of volcanic activity, large meteor impacts, things on that scale, not a bunch of smart monkeys running around burning shit for a hundred years. Planetary activities tend to be measured on cosmic scales which count time in the millions of years.

Humans think entirely too much of themselves if they think they can actually destabilize an entire planets atmosphere regulatory system in, what is to the planet, less then a blink of an eye. We are insignificant when compared to such cosmic scales.

Large meteors, mega-volcanoes - destablise instantly.

Glaciation feedback changes take tens of thousands of years.

Ecosystem changes (extinction of significant amounts of species due to environment change) can be anything from 10 - 1000 years or more for example when plants learnt to photosynthesise.

smart monkeys burning shit:

No problem if it was shit. Per capita per year mass limited to 200g*356 days = 70kg

But we have per capita per year usage of >10 tons CO2 equiv fossil fuels in developed countries.

That is 100X the smart monkey shit norm, and becomes significant when there are enough smart monkeys. Humans currently live, supported by technology, at a density impossible ever before in evolutionary history. That is a shed-load of shit. And 100X more CO2 form fossil fuels.

200 year timescale looks about right to me.

Still pushing the global warming BS?

Sea Level Was Higher During The Medieval Warm Period

It is currently several miles from the sea, but at the time when the Romans and Normans built the structures, the water lapped right up to the edge of the stone. The map below shows the bay 900 years ago, and the current seashore as a dashed line.

paperburn1 wrote:You make one incredibly important point. currently we are in a state that our population density is out of proportion with our available energy. If history has shown us anything its that when you reach this level in development; your civilization must find a denser source of energy or fall back to a more sustainable level. Maybe this is the real answer to the Fermi paradox.

Even if none of the fusion startups including polywell pan out that only leaves us:

Oil by fracking and tarsands; many decades estimated supply (could even add to that oil converted from coal by the Fischer–Tropsch or related process).Renewables maybe at some point will come into their own.Nuclear fission; reprocessing of "spent" fuel rods to prolong their life how many times? Improvements in mining techniques; understand the Japs are making progress learning how to extract Uranium from seawater. Breeder reactors; both with U to Pu or maybe breeding Thorium; several times more abundant than U; could last millennia if needed. The waste problem could be solved by converting long lived isotopes by irradiation to shorter lived ones; going from 10's of thousands of years of storage to a few hundred.And no doubt other things I haven't mentioned.

Last edited by williatw on Sun Jan 24, 2016 6:04 am, edited 1 time in total.